The Study Of Preparation Of Iron Nanocomposites And Their Application In Catalytic Degradation For Organic Dyes

Organic dye wastewater is one of the common industrial pollution.Due to the biological toxicity,high Chemical oxygen demand(COD)and Biochemical oxygen demand(BOD),complex chemical structures,high chroma and other characteristics,common treatment processes of industrial wastewater such as microbial degradation,physical adsorption,ozone oxidation and other technologies are not suitable for the treatment of organic dye wastewater.Therefore,it is necessary to develop new technologies,which are of great significance to the protection of natural environment and the conservation of water resources.In this thesis,MXene and MoS2,the two good electronic conductors were selected as the substrate materials to fix Fe3O4 nanoparticles on by one-step alkali thermal synthesis method and mussel-inspired bionic dopamine modification method,respectively.Two kinds of composite materials loaded with Fe3O4 nanoparticles with uniform size and uniform distribution were obtained.And the two conposites were used for highly efficient Fenton Reaction for the catalytic degradation of organic dyes,the influence of single factor on catalytic performance of catalyst was investigated by using control variable method,and the potential application of the two cmposites in catalytic degradation of organic dyes was evaluated in detail.The main research contents and results are as follows:(1)The magnetic composite(Ti3C2-MNPs)of Ti3C2 MXene loaded with nano Fe3O4 magnetic particle(MNPs)was synthesized by one-step alkaline thermal method,which was characterized by Scanning electron microscopy,Transmission electron microscopy,XRD,XPS and other techniques.The results showed that Fe3O4 nanoparticles with a size of about 5 nm were well dispersed on the surface of Ti3C2 MXene,MXene was not oxided into TiO2,there was no Fe2O3 and FeO.(2)In the experiments to test the degradation efficiency of organic dyes,the initial and immediate concentrations of organic dyes in the solution were measured by ultraviolet spectrophotometer,and the degradation efficiency of organic dyes was calculated.The results of catalytic degradation experiments showed:the best ratio of precursors Ti3AlC2 and ferric acetylacetonate was 1:1 for the best catalytic efficiency;when the hydrogen peroxide concentration at 50 mmol/L,the catalytic efficiency was best at the catalyst concentration at 0.9 g/L;when the catalytic concentration at 0.5 g/L,the catalytic efficiency was best at the hydrogen peroxide concentration at 10 mmol/L,the optimal temperature and pH was 40℃ and pH=3;under the optimal condition,with the concentration of hydrogen peroxide at 10 mmol/L,catalyst concentration at 50 mmol/L,pH was 3,the temperature was 40℃,Ti3C2-MNPs took 3 min to finish the absolutely catalytic degradation of methylthionine chloride in the solution;under the same condition,time needed for absolute degradation of rhodamine B,methyl orange,Congo red and methylthionine chloride,the four organic dyes with different structures were 7 min,12 min,7min and 6min,respectively.The catalytic performance of the catalyst could be maintained at 94%after recycling for five times.Besides that,quenching agents experiments and Electron spin resonance(ESR)spectra showed that hydrogen peroxide free radicals(·OH)and superoxide free radicals(·O2-)were involved in the degradation process.(3)With the characteration of dopamine self-polymerization in alkaline solution,taking the Mussels-inspired strategy to prepare magnetic two-dimensional MoS2-based magnetic composite material(MoS2-MNPs),SEM,XRD XPS and ather characterization were used to analyse the morphology,O element valence,phase composition and so on.The results showed Fe3O4 was well dispersed on the surface of MoS2 sheets by the coating effect of dopamine polymer,preventing the self-aggregation of Fe3O4 nano particles,causing the maintaince of high efficiency in the resuage.(4)The results of catalytic degradation performance of MoS2-MNPs showed that when MoS2-MNPs concentration at 0.1-0.9 g/L and the H2O2 concentration in the range of 10-90 mmol/L,MoS2-MNPS could hightly catalyze hydrogen peroxide into·OH and ·O2-,causing the quick degradation of methylene blue,catalyst concentration and hydrogen peroxide concentration caused negligible effect to the degradation efficiency;When the pH at 3-9,the degradation efficiency remained high,the effect from pH value was negligible,when the pH at 11,the degradation efficiency decreased obviously;quenching agent experiments and electron spin resonance(ESR)test indicated that it was·OH that played in the degradation process and then was·O2-;besides that,in the reusage experiments,MoS2-MNPs remained excellent catalytic performance in the fifth cyclic usage.